Search.hhowtodiy.com is a browser hijacker that will attempt to commandeer your browser search and homepage. The virus will send you to malicious websites to get money from you or infect your computer further. It may also prevent you from changing your settings back.
Search.hhowtodiy.com is usually installed through bundled software without you knowing. In this case, it is from the How To DIY extension. You have to remove it immediately before it infects your computer further.